Limits on how much you can change / reset your password

[stuartpb]

I ran into trouble when profiling Mashery because they stop letting you change passwords after doing it 3 times in a day.

I was thinking of adding password.quota.limit and password.quota.period for when sites have limits like this; it's a pretty important factor for Nilpass.

[stuartpb]

Putting this on future because it takes a lot of experiment / tracking infrastructure to profile, so it's not data that's just being left on the table right now the way that, say, not profiling elements is.